I'm sure this is also because the hard sciences are seen as just that - hard, and the people involved in the discipline have a certain vested interest in maintaining that image. If just anyone could major in physics, math, biology(at my school, one of the most highly dropped and difficult majors) etc., then the (insert hard science here) people wouldn't be able to sneer at all the Human Ecology majors. Perhaps not a conscious motivation - but, as Barbie says 'Math is Hard!!'